Move fern workflows to root workflows folder (#1273)

* Move fern workflows to root workflows folder

* Only run fern actions when docu has changed

.github/workflows/fern-check.yml

@@ -4,6 +4,8 @@ on:
   pull_request:
     branches:
       - main
+    paths:
+      - "fern/**"
       
 jobs:
   fern-check:

.github/workflows/preview-docs.yml

@@ -4,6 +4,8 @@ on:
   pull_request:
     branches:
       - main
+    paths:
+      - "fern/**"
 
 jobs:
   preview-docs:

.github/workflows/publish-docs.yml

@@ -4,6 +4,8 @@ on:
   push: 
     branches: 
       - main
+    paths:
+      - "fern/**"
 
 jobs:
   publish-docs: